Update docs/en/3-guides/3.3-how-to-upload-data.md

Chore: fix typo

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

Author: david-roper

docs/en/3-guides/3.3-how-to-upload-data.md

@@ -65,6 +65,6 @@ Open Data Capture allows you to visualize numeric measures over time in a single
 
     - **_Optional Data_**
 
-      Whenever data is optional within a form it can be left empty and still be properly submitted. Any optional data column in the csv template will have an "(optional)" tag attached to its sample data entry, which means any entry in the column can be left blank. This is usually done in that case of when one column value depends on another. For example, a sessionFailed column would be followed by a an optional reasonForFailure column.
+      Whenever data is optional within a form it can be left empty and still be properly submitted. Any optional data column in the csv template will have an "(optional)" tag attached to its sample data entry, which means any entry in the column can be left blank. This is usually done in that case of when one column value depends on another. For example, a sessionFailed column would be followed by an optional reasonForFailure column.
 
 </Steps>